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IPV6 and broadcast

hi

i have usually heard that IPv6 resolved the problem of broadcast

however today i read that the "neighbor discovery" ICMP message replaced the ARP request

but this "neighbor discovery" is using the multicast as destination address

and if i m not wrong the L2 switch will treat these multicast as broadcast , i mean it will send it to all active ports !

so how did IPv6 eliminates broadcast? we just changed the name ! but at the end the neighbor discovery message will reach all ports ! isn't it ?

thanks

1 REPLY
Cisco Employee

IPV6 and broadcast

One can argue that all-nodes multicast is essentially a broadcast, yes.

However if you check the RFCs neighbor solicitation and discovery are using both mcast IP and link-layer addressing, they can be subject to multicast distribution efficency mechanism on L2.

You can check the L3 format (rfc 4861 - section 4.3)  and L2-L3 address mapping (rfc 2464 section 7) .

As far as I know (and I have limited scope of what's out there) there is no such mechanism that anyone is implementing right now.

M.

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